A discovery of sporadic semidiurnal tide resonance in the western
equatorial Pacific thermocline prior to El Niño onset leads to a reinterpretation of the Tropical Hypothesis of global
change in multiple time scales.

The tropical hypothesis revisited: Is Pacific countercurrent consolidationthe
common mechanism of global cooling in interannual, millennial, and orbital time scales?

Abstract:Pacific countercurrent consolidation (PCC)
is proposed to be the common mechanism of El Niño – La Niña mediated climate change in interannual, millenial,
and orbital time scales, reflecting operation in a single Earth system. In short time scales, PCC follows a novel hypothesis
of El Niño – La Niña forcing in which internal tide resonance dissipates the vorticity that powers northward
Sverdrup transport, so the North Equatorial Countercurrent merges geostrophically into the Equatorial Undercurrent. The resulting
PCC reduces countercurrent shear surface friction to trigger eastward advection at El Niño onset. ITR is observed in
wavelet analysis of one hour resolution western Pacific thermocline temperature,revealing>8°C amplitude resonance in the semidiurnal tide band prior to El Niño onset in 1997, 2002 and 2006.
This ITR is independent of westerly wind bursts. Subsequently, persistent PCC prevents warm pool recharge, leading to an equatorially
symmetric La Niña mode with global cooling teleconnections. Proposed interannual and millennial time scale cycles in
higher tidal force are consistent with instrument and proxy records of global cooling phases. In orbital time scales, mutual
precession and obliquity mediated southward migration of the intertropical convergence zone also results in PCC, because the
North Equatorial Countercurrent follows the intertropical convergence zone. The mid-Pleistocene transition is evidence of
mutual obliquity-precession control, for this is when their phase relationship changes from 1:2 (40 thousand year cycles)
to 2:5 or 3:5 (80 or 120 thousand year cycles).